The present invention relates to the preparation of 2-pyrrolidone and N-acyl-2-pyrrolidone. The 2-pyrrolidone is useful for making synthetic fibers such as nylon fiber.
Prior art methods for producing pyrrolidone include the reaction of maleic anhydride with ammonia and hydrogen -- see U.S. Pat. No. 3,109,005; the reaction of succinic anhydride with ammonia and hydrogen -- see U.S. Pat. No. 3,080,077; and the reaction of gamma-butyrolactone with ammonia -- see U.S. Pat. No. 3,115,500.
It has also been disclosed that 2-pyrrolidone can be made by the reaction of allylamine with carbon monoxide using a cobalt catalyst -- see British Pat. No. 628,659 and Falbe et al., Chem. Ber. 98, 1928 (1965). British Pat. No. 1,028,097 states that it improves on the yields achieved in British Pat. No. 628,659 by using relatively large amounts of solvent -- that is, large parts of benzene or the like solvent per part of the allylamine feed. The British Pat. No. 1,028,097 patent reports a yield of 27 weight percent 2-pyrrolidone using one part benzene solvent per one part allylamine and a yield of 54% when using 30 parts by weight benzene per one part by weight allylamine at a temperature of 280.degree. C. and 300 atmospheres pressure. The British Pat. No. 1,028,097 states at pages 2-3:
"The catalyst used in the process according to the invention is a cobalt carbonyl compound. According to the U.K. patent specification No. 628,659 hydrogenation catalysts, for example nickel, may be used. It was found, however, that good yields of alpha-pyrrolidone can only be obtained with cobalt catalsyts." PA1 palladium chloride, PA1 palladium bromide, PA1 palladium iodide, PA1 palladium oxide, PA1 palladium acetate, PA1 palladium octanoate, PA1 palladium 2-ethylhexanoate, PA1 palladium naphthenate and PA1 palladium nitrate. PA1 palladium acetylacetonate, PA1 bistriphenylphosphine-palladium-chloride, PA1 tetrakistriphenylphosphine-palladium, and PA1 bisbenzonitrile-palladium-chloride.
Another patent disclosing cyclocarbonylation of allylamine to 2-pyrrolidone is U.S. Pat. No. 3,714,185. U.S. Pat. No. 3,714,185 states that the prior art suggested to catalyze the cyclocarbonylation of allylamine to 2-pyrrolidone with salts such as the halides, acetates and nitrates or carbonyls of cobalt, rhodium, nickel, iron, platinum and palladium.
According to U.S. Pat. No. 3,714,185, a rhodium or cobalt catalyst is used for the cyclocarbonylation reaction. The U.S. Pat. No. 3,714,185 discloses the use of a wide range of ligands for the catalyst including phosphine ligands such as triphenylphosphine. The U.S. Pat. No. 3,714,185 also mentions that it is an object of the U.S. Pat. No. 3,714,185 process to provide a new method for the carbonylation of allylamines, allylamides and allylalcohols to produce the corresponding lactams, imides and lactones, respectively. The reaction temperature disclosed in the U.S. Pat. No. 3,714,185 are 120.degree.-290.degree. C. and preferably 150.degree.-200.degree. C.